You clearly aren't familiar with Simmons' writing style. For instance, in my opinion the best thing he's even written was the Oscar Robertson section in The Book of Basketball. He manages, in the course of only a handful of pages, to just about perfectly capture the difficult balance of the O's legacy. His enormous talents, his extremely difficult personality, which got in the way of success, and of course the way that the ever-present racism of the era he played in deeply affected both those things. And I'm not the only one who feels that way. In the second edition, Simmons includes a footnote from Jason Whitlock, one of the most vocal (and, it must be said, controversial) media members about racial issues in sports, and he says essentially the same thing. My point? Simmons uses that language throughout the section. It's his style. He's informal, he's straightforward, he's self-deprecating, and he's funny, and it's why he's been so successful and will continue to be. His language in the letter would be troublesome if it was a departure from his usual writing, but it's not, and so as an avid reader I don't take it as flippant or dismissive.
As for your comment about it being 2700 words too long, the original post here is the only professionally published article I've read on the subject since Simmons' statement (which includes articles on Salon, Washington Post, Deadspin, etc.) which continues to phrase the events as though Hannan acted maliciously. The reason for the length of Simmons' apology was to make clear that Hannan and the editorial staff were extremely unfamiliar with trans* issues, and that it was that lack of education, and not personal hate or bigotry, that caused Hannan to make the mistakes (which Simmons, it should be noted, takes full responsibility for) he did. He didn't realize how grave it is to out someone in the trans* community in life or death, and to him it fit the narrative he found, of an inventor whose life was a complete lie. Again, he didn't understand that keeping a gender identity secret is done out of necessity in our culture, and is not in any way a statement of one's personal veracity. Grantland also published an op-ed by ESPN's Christina Kahrl, who is transgender, in which she eviscerates Hannan and the editorial staff's actions (http://grantland.com/features/what-grantland-got-wrong/). Note that at no point in her attack on Hannan's actions does she attribute it to maliciousness. To quote, "revealing her gender identity was ultimately as dangerous as it was thoughtless."
EDIT: I guess I should I add something, just so I don't get accused of anything. I attended one of the most progressive high schools in the country, and now attend one of the most progressive colleges, and know many LGBTQ and trans* individuals, with a few of the former counted among my closest friends. I believe that one's identity is theirs and theirs alone until they choose (if ever) to come out, and I also strongly believe that active sexual and gender discrimination is a hate-crime. My point is not that Grantland was not horribly horribly wrong. They were. My point is that it was a lack of education that caused their errors, and that the opportunity should be used to continue educating, which Simmons' piece, even if it seems at times to be attempting to shoehorn in an excuse, does. I know the errors they made, but I'm sure the vast majority of Grantland's readership does not.
As for your comment about it being 2700 words too long, the original post here is the only professionally published article I've read on the subject since Simmons' statement (which includes articles on Salon, Washington Post, Deadspin, etc.) which continues to phrase the events as though Hannan acted maliciously. The reason for the length of Simmons' apology was to make clear that Hannan and the editorial staff were extremely unfamiliar with trans* issues, and that it was that lack of education, and not personal hate or bigotry, that caused Hannan to make the mistakes (which Simmons, it should be noted, takes full responsibility for) he did. He didn't realize how grave it is to out someone in the trans* community in life or death, and to him it fit the narrative he found, of an inventor whose life was a complete lie. Again, he didn't understand that keeping a gender identity secret is done out of necessity in our culture, and is not in any way a statement of one's personal veracity. Grantland also published an op-ed by ESPN's Christina Kahrl, who is transgender, in which she eviscerates Hannan and the editorial staff's actions (http://grantland.com/features/what-grantland-got-wrong/). Note that at no point in her attack on Hannan's actions does she attribute it to maliciousness. To quote, "revealing her gender identity was ultimately as dangerous as it was thoughtless."
EDIT: I guess I should I add something, just so I don't get accused of anything. I attended one of the most progressive high schools in the country, and now attend one of the most progressive colleges, and know many LGBTQ and trans* individuals, with a few of the former counted among my closest friends. I believe that one's identity is theirs and theirs alone until they choose (if ever) to come out, and I also strongly believe that active sexual and gender discrimination is a hate-crime. My point is not that Grantland was not horribly horribly wrong. They were. My point is that it was a lack of education that caused their errors, and that the opportunity should be used to continue educating, which Simmons' piece, even if it seems at times to be attempting to shoehorn in an excuse, does. I know the errors they made, but I'm sure the vast majority of Grantland's readership does not.